During the 2005 General Election, Labour took a lot of damage on the issue of immigration. The Conservatives had a series of posters asking "Are you thinking what we're thinking?" The one that most struck a chord with the electorate was: "It's not racist to impose limits on immigration."

In many ways it would frame the next decade of British politics – setting up an issue that Gordon Brown did not understand and couldn’t answer and setting the scene for the rise of Ukip, and, indeed, the very referendum on the European Union that we are presently in the midst of.

“There are no easy answers to immigration that can be imported to the UK”

The problem for the Tories was that they had no credibility with the electorate – nothing they could say could win over swing voters. The story is told of a focus group in which Tory plans for controlling immigration were set out but with no party label attached. People loved them and asked: "When did Tony Blair say this?"

"I also understand concern over immigration controls. We will put in place strict controls that work. They will be part of our first legislative programme if we are re-elected on May 5. These controls will include the type of points system used in Australia, for example, to help ensure our economy gets the skills we need."

In many ways this still stands as the best expression of what the public believe would be the best form of immigration control: of course we need people to come and live and work here, but they must be qualified, and they must be the best.

The points-based system appears to guarantee this, and the fact that it is used by Australia is a further seal of approval. The country is renowned not just for a vigorous public debate on migration, but also for its well defended borders.

The Australian system is simply described. There are three ways to move into the country:

1) As a refugee

Via the official route for refugees, as described under the 1951 Convention on refugees. Come illegally though, governments – both Labor and Coalition say unequivocally – and you will not get to stay.

2) Sponsored by an employer to fill a job

This is fairly straightforward and makes sense. Not only will you not have recourse to public funds as you have a job, but you have passed a test of quality administered by the employer too.

3) The points-based system

Individuals need to apply as one of a specified list of skilled professions. Their skills need to be assessed by "an independent assessing authority for their nominated occupation". They must also be a member of an appropriate professional association. There is an English test too.

This system also treats student migration separately as "temporary migration" and controls numbers not with an arbitrary cap, but by a risk assessment based on the country from which students come. This flexibility means that Higher Education is Australia’s fourth largest export.

So far, so good, but what does it mean in practice? Actually, very high levels of migration.

Take refugees – one by-product of the tough approach to refugees who arrive illegally is a very generous humanitarian settlement rate. 20,000 refugees get to settle in Australia a year – the country is over a third of the population of the UK so the equivalent here would be 50,000 a year.

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The number of places for the Migration Programme was 190,000 in 2014/15. Taken together that is a planned migration target equivalent to over half a million a year – or as the Australian Bureau of Statistics puts it "one international [migrant] every 2 minutes and 39 seconds". Not, one thinks, what voters mean when they say they would like a fully points-based system for Britain.

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There are no easy answers to immigration that can be imported to the UK. Different countries have different needs. Australia is an under-populated continent with the capacity to grow much larger. At the beginning of the 20th century the population was under 4 million, smaller than Scotland. Britain is an ageing society that needs skilled workers, for sure, but also unskilled workers for agricultural labour.

In the end, the question will come down to trust and a track-record on immigration that chimes with their concerns about the numbers entering the UK.

Who will voters trust the most on immigration? Cameron or Boris? Corbyn or Farage? Time will tell.